Six ways to silence squeaky stairs.
Stairway squeaks are usually caused by a loose tread rubbing against
a riser or stringer. If the noise comes from where you step,
concentrate your repair efforts there. If noise comes from one side
when you step in the center, or from the rear of the tread when you step
at the front, first secure the place where you step, then move to the
apparent source of the noise. If you can, work from below so repairs
won't show. Otherwise, first try lubricating stairs with powdered
graphite or talcum powder. Forcefully blow the powder into the joints,
especially where the backs of the treads meet the risers.
If this doen't help, try one of the repairs shown here. When
using wedges, you'll have to remove any shoe molding first. After
driving in wedges, use a utility knife to cut them flush with the riser.
Then replace molding to conceal the wedges.